The invention relates to a vortex generator to be installed on an outer flow surface of an aircraft, as well as to an engine nacelle of an aircraft with a vortex generator arrangement.
In view of the performance of an aircraft, in particular of a commercial aircraft or transport aircraft with a heavy take-off weight, the maximum achievable lift in the takeoff and landing phase is of particular importance. Said lift depends on the size and geometry of the wing, and, to a limited extent, on the airflow separation at the top of the wing profile, which starts as the angle of attack of the aircraft increases. In order to increase the maximum achievable lift, slats or leading-edge flaps are provided as high-lift devices at the wing, usually at its front, while trailing-edge flaps are provided at the rear of the wing. With an advantageous design of these high-lift elements it is possible to shift the commencement of airflow separation on the wing to significantly higher angles of attack.
There is a further effective measure in order to shift the maximum achievable lift to still higher angles of attack, namely in that by means of suitably designed vortex generators fields of vorticity are generated at the top of the wing, which fields of vorticity increase in intensity as the angle of attack of the aircraft increases. The outside of the engine nacelle of engines that are arranged on the wing is a suitable location for the installation of such vortex generators. With an optimal arrangement and at high angles of attack, such vortex generators, which are known as nacelle strakes or chines, generate a powerful vortex that flows over the wing, where on a slat in front of said wing it delays airflow separation until the aircraft flies at greater angles of attack.
According to U.S. Pat. No. 4,540,143, depending on a particular application, at least a combination, comprising a fin-shaped vortex generator and a boundary layer fence that continues from said vortex generator without a transition and at an even height, is provided on one side or on both sides of the engine nacelle. With such combinations comprising a fin-shaped vortex generator and a boundary layer fence, it is possible not also to achieve the formation of one or several vortices, which as far as possible are spatially limited, but also to limit the propagation, in the direction of the wingspan, of airflow separation which occurs as a result of the front upper edge of the engine nacelle and extends from that location over the wing, in that one or several vortex/vortices is/are formed that is/are spatially limited as far as possible.
From U.S. Pat. No. 3,744,745 it is known to provide a vortex generator on each side of the engine nacelle. In this way an increase in the intensity of the downwash flow field is to be achieved.